1. Technical Field
The present invention relates to device that provides phone services to phones plugged to a residential phone wiring that is not coupled to a central office.
2. Description of Related Art
On a local loop, where a telephone exchange is connected to a phone located on customer premises, the analogue voice services, or plain old telephone service, noted POTS, typically use the 300 Hz to 3400 Hz frequency range. The digital subscriber line technology uses the upper frequencies and permits to bring information over the copper wire that was originally intended only for the voice transport over the public switched telephone network. Customer premises receive the analogue phone services on the lower frequency band, and data services on the upper frequency band. It requires a DSL modem to communicate with the digital subscriber line access multiplexer, noted DSLAM, located in the local phone company's central office. It also usually requires the analogue phones to be plugged to the residential phone wire through a low pass filter. Then the analogue phone is coupled to the phone service central office, or foreign exchange station, noted FXS, and the DSL modem is coupled to the DSLAM. On the same local loop, two channels coexist: the analogue phone channel and the DSL channel.
The DSL technology permits the customer premises to access the Internet through the internet protocol, noted IP. Usually, a DSL gateway located in the premises comprises a LAN interface and devices connected to the LAN may access the Internet. They may run different kinds of applications such as voice over IP, noted VoIP. VoIP is performed with applications running on personal computers or with dedicated VoIP terminals connected to the LAN. The LAN may be a wired network such as an Ethernet network or a wireless network such as a WiFi network. The voice service with VoIP is not using the public switched telephone network; it is running over Internet.
Some gateways comprise an analogue phone interface, or FXS interface, allowing to connect an analogue phone. This permits the phone to be coupled to the FXS located in the central office in order to access the POTS services, and to use the same phone services as the analogue phones plugged to the residential phone wire. Some gateways also comprise phone subscriber line interface means, and act as a FXS. This permits the phone connected to the FXS interface of the gateway to be coupled to the FXS located in the gateway, and perform voice services with VoIP.
When the customer premises are no longer connected to the telephone service central office, the phones plugged to the residential phone wire can no longer access the POTS services. A gateway that comprises subscriber line interface means still permits the phone plugged to the FXS interface to perform voice service with VoIP. To authorize the phones plugged to the residential phone wire to perform voice services with VoIP through the gateway, a possibility is to connect the entire residential phone wire to the FXS interface of the residential gateway. This requires the gateway to be located at the same place as the MPOE, and to connect the entire residential phone wire to the FXS interface of the gateway.